Tenement Housing For Dummies!
I'm sure there are as many ways to handle human housing as there are players, but I wanted to share my own method of handling the challenge.
First, you Designate your floor-plan by Channeling it into a flattened, cleared area.
Once it's dug out, you carefully roof over the dug rooms with Constructed Floors. Access to the basement rooms should be via Constructed UP/DOWN stairways. You will, of course, need lots of blocks.
Now for the trick: Go to Construct Walls, but enable Box Select by pressing 'b.' Make a big 'ol rectangle over the previously built or designated roofs. Did I mention the blocks? You'll need them. Have 3 or 4 brick-splitters going.
The wall placement will automatically skip over the previous constructions, and fill in each wall with a single stroke of the 'enter' key.
Handy!
This building is also easily expandable; just go up a level, and extend the up/down stairway. Repeat the process (placing the floors, then box selecting the walls), and you have an easily built second floor. Of course, this being dwarf fortress, you'll still need to babysit your humans as they build it, but it's worth the ease and safety of construction. If you construct it out of marble blocks, even small rooms will be luxurious enough to keep your humans happy. It also looks, in my opinion, awesome.
That's my two cents. I'm sure most of you have your own means of doing such things, but I figure if I can save one person some trouble, it'll be worth the effort ^_^